DE3803997A1 - DEVICE FOR THE CONTINUOUS PRODUCTION OF MULTILAYER BOARDS - Google Patents

Description

The invention relates to a device for continuous production multilayer printed circuit boards according to the preamble of patent claim 1.

Printed circuit boards have long been used in the electronics and electrical industry for the assembly of the components and their electrical connection under used each other. Serve as the starting material for such printed circuit boards copper-clad laminates. These copper-clad laminates consist of a laminate core, this on at least one surface Laminate core is an electrolytically deposited copper foil of high Purity level that is firmly connected to this surface. The Laminate core in turn consists of individual layers of precon dense resin soaked carrier materials together, the so-called Prepreg. This prepreg consists, for example, of individual layers of Epoxy resin impregnated glass fiber fabric. The prepreg is exposed from heat and pressure with the copper foils to the copper-clad laminate pressed. In the case of such a copper-clad laminate, the layer serves core of material as carrier and insulation material, the copper layer to the Her provision of conductor tracks. The production of these conductor tracks on the copper-clad laminate, i.e. the completion of the circuit board, is usually done by etching.

Due to the ever increasing integration density of the electronic Blocks with a large number of connections are used instead of de multilayer printed circuit boards are increasingly used. These Multilayer circuit boards consist of individual, the respective conductor track Printed circuit boards containing patterns, which fit exactly one above the other, whereby there is a layer of layer between two individual circuit boards fabric. The circuit boards on the two surfaces are called multilayer outer layers, while the intermediate circuit board ten multilayer inner layers. With these multilayer boards one advantageously achieves greater freedom of movement and density in the conductor track, as this for crossing-free guidance on several Layers can be arranged.  

DE-OS 33 07 057 is a continuous process and a pre direction known for the production of multilayer printed circuit boards. With this Processes are made on the edges of a copper-clad laminate sheet is continuously produced on a double belt press, after Ver let the double belt press introduce fixing holes that have a constant Distance from each other. The further processing of this copper cladding Laminate sheets for multilayer printed circuit boards are made in reference to these fixing holes, whereby two approaches are mentioned.

The first step is to use the copper-clad laminate sheet of the fixing holes cut into individual plates, which are then separated by etching, drilling, and the like with the corresponding conductor track pattern, using the fixing holes as a reference for the position of the conductor pattern of the respective multilayer inner layer. In the In the second procedure, a conductor pattern is repeated in each case Reference to the fixing holes on the copper-clad laminate sheet made so that you get a laminate web of regular one after the other arranged multilayer inner layers, the multilayer inner layer sheet.

The device for continuous manufacture shown in DE-OS 33 07 057 The position of multilayer printed circuit boards consists of a double belt press with two endless pin chains rotating synchronously over sprockets, each at an edge of the press zone of the double belt press be passed through. Unwinding units are in front of the double belt press arranged for prepreg sheets. That according to the first procedure Multilayer inner layers are made according to the desired order build the multilayer circuit board using the fixing holes on the pin chain applied, one between each two multilayer inner layers Prepreg web that is unwound from unwinding units is carried along. This package of multilayer inner layers with prepreg Lanes become doubles thanks to the continuously advancing pin chain belt press transported and in this under the influence of heat and  Pressure pressed to the multilayer circuit board. The according to the second pre multilayered inner layers are produced before the Double belt press according to the structure of the multilayer circuit board from Unwinding units unwound and by means of the fixing holes on the pin chain, with two multilayer layers Inner layer webs a prepreg web, which abge from an unwinding roll is wrapped. This package of multilayer inner layers with Intermediate prepreg webs will move from the pin chain towards Double belt press transported and in this to a multilayer web pressed. There is a cross saw behind the double belt press the individual multilayer circuit boards from the multilayer web in turn Saw out the reference to the fixing holes.

A disadvantage of this known device is the complex control of the synchronous operation of the two pin chains and the synchronism of the pin chains with the press belts of the double belt press. Low speed differences between the pin chains with each other or to the press belts lead to a shift of the individual multilayer inner layers or multilayer inner layer webs and to wrinkles, which ultimately makes the multilayer printed circuit board unusable. Furthermore, an exact parallel guidance of the pin chains to the press belts is required to avoid rejects. Transport and control movements can cause vibrations of the pin chains and fluctuations in the pretension of the chain can cause play between the chain links, which affects the parallel guidance of the two pin chains. Moreover, the production of the pin chain within the required narrow tolerances mm from a maximum of about ¹ / _100th that is required for the production of multilayer printed circuit boards, very difficult and very expensive.

Starting from this prior art, the invention is based on the object reasons, the device for the continuous production of multilayer Develop circuit boards so that on the two of the double tape press independent pin chains can be dispensed with.  

The solution to this problem is given by the in the patent technical teaching described 1.

The advantages that can be achieved with the invention are that none Differences between the feed speeds in the fixer holes on the two edges of the multilayer inner layers or multilayer Protrusions engaging inner layers and in relation to the Press belts can occur. This eliminates the need for a complex Control or regulating device for synchronizing the feed speed of the projections with that of the press belts. Shifts of individual multilayer inner layers are thus avoided and the end shot is reduced. The additional guidance facilities through the Double belt press, which are required for the pin chains, are eliminated because the projections are integrated into the press belt to form a pin belt. The Press belt with the integrated protrusions itself is structurally simpler and also cheaper to manufacture than the pin chains.

A preferred embodiment of the invention is in the drawings shown and is described in more detail below. It shows

Fig. 1 shows an apparatus for the production of copper-clad laminates,

Fig. 2 is a multilayer inner layer web with fixing holes in plan view,

Fig. 3 shows a device for the continuous manufacture of multilayer printed circuit boards of multilayer inner layer webs,

Fig. 4 shows a device for the continuous manufacture of multilayer printed circuit boards of multilayer inner layers,

Fig. 5 shows several embodiments for the pen tape and

Fig. 6 schematically shows a section through a double belt press with pin band.

Schematically in Fig. 1 shown continuously operating Vorrich processing for the production of copper-clad laminates is known from DE-OS 33 07 057 and consists of a continuously operating double belt press 1, a punching device 2 for the fixing holes 17, unwinding units 3 and 4 with supply rolls 5 for the prepreg and 6, 7 for the copper foil, a winding station 8 with rollers 9 for thin copper-clad laminate webs, moving scissors 10 and a control cabinet 13 with a data display device 14 .

The prepreg webs for the laminate core, which are made of resin-coated, precondensed fabric, are drawn off from rolls 5 in the unwinding unit 3 and are combined with copper foils which are pulled off from rolls 6, 7 in the unwinding unit 4 to form a layered structure 15 such that the prepreg webs between two copper foil sheets lie. This layered structure 15 is pressed into the copper-clad laminate web 16 in the double belt press 1 under the action of heat and surface pressure. In this punching device 2 , fixing holes 17 , which are drawn in excessively large in FIG. 1 for illustrative reasons, are then introduced at regular intervals along the two edges of the copper-clad laminate web 16 . A computer in the control cabinet 13 , which is supplied with inputs by the operator via the data display device 14 , controls the entire production process and also the punching of the individual fixing holes 17 at a frequency which is dependent on the feed speed of the copper-clad laminate web 16 in the double belt press 1 . This ensures that the distances between the individual fixing holes 17 remain the same under all operating conditions of the device for producing copper-clad laminates, which is essential for the precise production of the multilayer printed circuit boards. In the punching device 2 there is also a cooling and cleaning device in which the copper-clad laminate web 16 is cooled and the surface thereof is cleaned.

In the winding station 8 , the copper-clad laminate web 16 is wound up on rolls 9 if it is a thin, flexible copper-clad laminate web. Alternatively, the copper-clad laminate web 16 can be divided with the scissors 10 into copper-clad plates 11, which are stacked in pallets 12 .

These copper-clad laminate webs 16 , which can be wound on rolls 9 , or copper-clad plates 11 are then processed further to multilayer printed circuit boards. In Fig. 2 a top view is shown on such a copper-clad laminate web 16 with the inserted at the two edges in the punching device 2 fixing holes 17th The fixing holes 17 , the center points of which are at a constant distance from one another, are located along a hole edge 18 . With reference to these fixing holes 17 , etching resist areas 19 can then be defined for etching the desired conductor pattern. On each of these etch resist surfaces 19 , the desired conductor pattern of a multilayer inner layer of the multilayer circuit board is printed as known or applied with photographic means or the like. During the subsequent etching of the copper layer of the copper-clad laminate track 16 , the copper is etched away to such an extent that only the conductor tracks remain. Advantageously, the same conductor pattern of a single multilayer inner layer is always produced on the copper-clad laminate path 16 on the etching resist surfaces 19 one behind the other, so that a corresponding multilayer inner layer path is obtained, on which the same conductor pattern is regularly arranged. The further processing, such as drilling, milling, etc., of these multilayer inner layers located on the multilayer inner layer web likewise takes place in reference to the fixing holes 17 . Such a multilayer inner layer web is made for each multilayer inner layer of the multilayer circuit board.

If the copper-clad laminate sheet 16 is already divided into individual copper-clad plates 11 , the respective conductor pattern of a multilayer inner layer is applied to the copper-clad plate 11 in reference to the fixing holes 17 and this copper-clad plate 11 is then etched, drilled, punched, milled and The same is further processed to correspond to the multilayer inner layer, the fixing holes 17 serving as reference in each case.

To compress the individual multilayer inner layer webs obtained as described to form a multilayer web or the individual multilayer inner layers to form a multilayer printed circuit board, the corresponding multilayer inner layer webs or multilayer inner layers are centered on the fixing holes in the desired order, between the multilayers - A prepreg sheet was arranged in each of the inner layers, a prepreg sheet and copper foil for the multilayer outer layer were placed on the surface of this layer structure and then exposed to pressure and heat. The devices used for this are shown in more detail in FIGS. 3 and 4.

The device shown schematically in FIG. 3 for the production of multi-layer printed circuit boards consists of a continuously operating double belt press 20 , a plurality of winding units 21 to 26 arranged in front of this double belt press, a cooling and cleaning device 27 arranged behind the double belt press 20 and a cross saw 28 The entire production process of the device shown in FIG. 3 is controlled by a computer in a control cabinet 29 . The operator inputs for the computer in the control cabinet 29 via a data display device 30 .

The double belt press 20 , as can be seen in FIG. 6, has two press belts 31, 32 arranged one above the other in a press frame, which are guided endlessly over two deflection rollers 33, 34 and 35, 36 , respectively. The press belts 31, 32 are tensioned by means of hydraulic cylinders 67 . The deflection rollers 33, 34, 35, 36 are in turn rotatably mounted in bearing bridges 37, 38 fastened to the press frame (see FIG. 3). The structure of the press frame for such a double belt press is known per se and can be found, for example, in DE-OS 32 34 082. The lower press belt 32 is pulled out in front of the double belt press 20 by the lower bearing bridge 38 and the associated part 39 of the press frame at the inlet into the Doppelbandpres se 20 are extended in the horizontal direction and the deflection drum 36 for the press belt 32 is at the extreme end of this extension . Since by the part located outside of the double belt press 20 of the press belt 32 forms a conveyor for transporting in the double belt press 20 to trans multilayer Innenlagen- and prepreg sheets. The lower press band 32 is provided along its two edges with projections 40 formed as pin teeth, which have exactly the same distance as the fixing holes 17 of the edge 18 of the copper-clad laminate sheet 16 and the diameter of the fixing holes 17 , that is, the pin teeth form to the fixing holes 17 corresponding projections 40 arranged on the press belt 32 . For reasons of clarity, only some of these pin teeth are shown in FIG. 6.

As can be seen in FIG. 3, an unwinding unit 21 is attached in front of the deflection roller 36 , which contains a roller 41 for an electrolytically separated copper foil and a roller 42 for the prepreg. From the roll 41 , the copper foil is continuously pulled off and guided on the deflection drum 36 onto the press belt 32 . A prepreg web unwound from the roll 42 is placed on this copper foil and this is transported together with the press belt in the direction of the double belt press 20 . During this transport, a first multilayer inner layer web is unwound from a roll 43 in the unwinding unit 22 and placed with the fixing holes 17 on the pin teeth 40 of the press belt 32 . A prepreg web, which is unwound from a roll 44 in the unwinding unit 23 , is then placed on this multilayer inner layer web. There then follow further multilayer inner layer webs, which are wound up from rolls 45 in unwinding units 24 and are separated by prepreg webs 25 drawn off from rolls 46 in unwinding units. The number of these multilayer inner layer webs and thus the unwinding units 24, 25 is determined according to the desired structure of the multilayer circuit board. The Zen tration of the individual multilayer inner layers one above the other is achieved with the help of pin teeth 40 which engage in the corresponding fixing holes 17 on the edge 18 of the multilayer inner layer webs. It is only necessary at the beginning of each roll for the multilayer inner layer, to lay this on the underlying multilayer inner layer according to the conductor pattern that is applied in reference to the fixing holes 17 , since the conductor patterns on each multilayer inner layer in regular Follow distances one behind the other. Finally, a copper foil is placed on the top prepreg layer, which is fed from a roller 47 in the unwinding unit 26 via the deflection drum 34 . The inlet-side deflection drums 34 and 36 are designed to be heatable, as is known, and thus preheat the copper foils to avoid wrinkles. For cleaning the copper foil surfaces can be attached to the inlet-side deflection drums 34 and 36 cleaning devices 48 , which remove dust and dirt from the copper foils. Such cleaning devices 48 are described in DE-OS 35 33 413. Instead of the upper and lower copper foil, already finished multilayer outer layers, which also have fixing holes, can be applied.

This layered structure 68 , which is formed from the multilayer inner layer webs separated by prepreg webs and from copper foils which abut the surface prepreg webs, is placed in the double belt press 20 between the two press belts 31, 32 under the action of surface pressure and heat simultaneous promotion by the double belt press 20 pressed. To exert the surface pressure on the layered structure 68 be on the back of the press belts 31, 32 pressure plates 69, 70 , of which a pressing pressure is transmitted via fluid or mechanical means to the press belt 31, 32 (see Fig. 6). When pressure is transferred using fluid means, annular seals 71 are arranged in the pressure plate 69 , which have a surface that slidably touches the inside of the press belt of the 31 . As a result, a pressure chamber 72 is formed between these seals 71 , the pressure plate 69 and the inside of the press belt 31 , in which a fluid medium is introduced under pressure. In the pressure transmission by mechanical means located on the pressure plate 70 stationarily arranged rollers 73, which transfer the pressure from the pressure plate 70 to the inside of the press belt 32nd

The pin teeth 40 of the press belt 32 engaging in the fixing holes 17 hold the multilayer inner layer webs fixed even under the pressing pressure, so that shifting or discarding of individual multilayer inner layers is excluded and these lie one above the other with a precise fit. If desired, a cooling zone can then be integrated in the double belt press, in which the layered structure 68 is cooled under surface pressure. At the outlet of the double belt press 20 , the resin of the prepreg webs has hardened and connects the individual webs of the layer structure to one another to form a compact multilayer web 49 , in which the individual multilayer printed circuit boards are arranged one behind the other at regular intervals. As can be seen in FIG. 3, this multilayer web 49 is then passed through a cleaning and cooling device 27 in which the surfaces of the multilayer web consisting of copper foil are cleaned with a solvent. Behind the cooling device 27 is a cross saw 28 , in which the individual multilayer printed circuit boards are cut out of the multilayer web 49 . The multilayer circuit boards can then be stacked on pallets for removal. The conductor track patterns of the multilayer outer layers can already be produced behind the cooling device 27 in a processing station (not shown in FIG. 3) in reference to the fixing holes 17 . Alternatively, these conductor track patterns of the multilayer outer layers can also only be produced after the multilayer track 49 has already been divided into individual multilayer circuit boards in the cross saw 28 . The edge of the hole 18 is expediently only trimmed when the multilayer outer layer has been finished.

In FIG. 4 a further embodiment is a pre inventive device shown for the production of multilayer printed circuit boards. The double belt press 20 is substantially identical to that of Fig. 3 or Fig. 6 constructed. Instead of multilayer inner layer webs, however, individual multilayer inner layers are now pressed to form a multilayer printed circuit board. For this purpose, 38 support plates 51 are placed on the lower bearing bridge, on each of which there is a stack 52 of the same multilayer inner layers. The order of the stacks 52 corresponds to the desired order of the multilayer inner layers in the multilayer circuit board. On the side of the press belt 32 opposite the carrier plates 51 there are unwinding units 50 for rolls 54 of prepreg webs.

In the device shown in FIG. 4, a copper foil is unwound from a roll 41 in an unwinding unit 21 and placed on the press belt 32 . A prepreg web, which is unwound from a roll 42 in the unwinding unit 21 , is arranged on this copper foil. At closing, the first multilayer inner layer is placed on the prepreg web from the stack 52 by means of a laying device 53 , the pin teeth 40 engaging in the fixing holes 17 on the edge 18 of the hole. The placement device 53 can for example consist of a movable vacuum suction plate. On this first multilayer inner layer, a prepreg web, which is drawn off from a roll 54 in an unwinding unit 50 , is layered. The next multilayer inner layer is then placed on the prepreg web by the next stack 52 by means of a laying device 53 , the second multilayer inner layer being arranged through the fixing holes 17 in a centered manner above the first multilayer inner layer. The pin teeth 40 also engage in the fixing holes 17 of the second multi-layer inner layer. This is followed by further prepreg webs of rolls 54 from the unwinding unit 50, alternating with further multilayer interior layers from the stacks 52 . A prepreg web and then a copper foil from a roll 47 from an unwinding device 26 are in turn placed on the top multilayer inner layer. This consisting of the multilayer inner layers, prepreg sheets and copper foils layer 68 is transported by the press belt 32 into the double belt press 20 and pressed therein with surface pressure and heat to form a multilayer sheet 55 , the pin teeth 40 of the press belt 32 hold individual multilayer inner layers fixed to each other. After the multilayer web 55 has left the double belt press 20 , the individual multilayer printed circuit boards are cut out by means of a cross-saw 28 , the fixing holes 17 again serving as a reference. In reference to the fixing holes 17 , the conductor track patterns for the multilayer outer layers are then introduced into the copper foils on the surfaces of the multilayer plates. The fixing holes 17 of the edge 18 of the hole can then be trimmed if they are no longer needed. The multilayer boards are stacked on pallets for transport.

In Fig. 5, several embodiments are shown for the pin with teeth than corresponding to the fixing holes 17 provided projections 40 press belt 32nd In a first embodiment, the pin tooth 56 , which essentially has a cylindrical body with a tapering, conical upper end, is connected to the press belt 32 by a weld 57 . The pin tooth 56 can just as well be soldered to the press belt. The tapered end of the pin tooth 56 facilitates the placement of the multilayer inner layers on the pin teeth in the fixing holes 17th However, the pin tooth can also have another expedient shape, for example a cylinder without a tip at the end, as shown by reference number 58 . This pin tooth 58 is attached to the press belt 32 by means of an adhesive layer 59 . The pin tooth 60 is screwed onto the press belt. For this purpose, the press belt 32 has a through hole 61 at the fastening point, and the pin tooth 60 has a threaded hole 63 . By means of a countersunk screw 62 , the pin tooth 60 is now screwed from the side of the press belt 32 remote from the pin tooth 60 to the press belt 32 , the head of the screw 62 forming a flat surface with the press belt 32 . In another fastening option, a cylindrical pin 65 is welded to the press belt. The pin tooth 64 has a groove 66 which is circular in cross section, the diameter of which corresponds exactly to the diameter of the pin 65 and is fitted with this groove 66 onto the pin 65 . The two last-mentioned exemplary embodiments for the pin tooth 60 and 64 have the advantage that they are easily exchangeable. As a result, the pin teeth can easily be replaced by others with different heights, should this be necessary due to the different thicknesses of the multilayer printed circuit boards to be produced.

The advanced lower press belt 32 facilitates the placement of the multilayer inner layers. However, it can also be a normal press belt with pin teeth, which is not pulled out of the double belt press. Instead of the lower press belt, the upper press belt 31 can also be provided with the pin teeth, or both press belts 31 and 32 can be provided with pin teeth. It is essential to the invention that at least one press belt of the double belt press has projections connected to it, which are arranged at regular intervals and correspond to the fixing holes 17 of the hole edge 18 of the copper-clad laminate web 16 .

Claims (18)

1. Device for the continuous production of multilayer printed circuit boards with a two endless, in a press frame arranged one above the other and guided over two guide drums press belts possessing double belt press for pressing multilayer inner layers, at the edges of which fixing holes are made, one in front of the double belt press Unwinding units for the multilayer inner layer webs lying on a roll with intermediate unwinding units for the prepreg webs or laying devices for the multilayer inner layers present as a plate with intermediate unwinding units for the prepreg webs and with means engaging in the fixing holes, which allow a precisely fitting superimposition of the multilayer inner layers to form a multilayer structure and to fix the multilayer inner layers of this layer structure during pressing in the double belt press , dadurc h characterized in that the means engaging in the fixing holes ( 17 ) consist of projections ( 40 ) which are arranged on at least one press belt ( 31, 32 ) of the double belt press ( 20 ) on at least one edge at regular intervals on the outside of the press belt ( 31, 32 ) are attached and that these projections ( 40 ) correspond to the fixing holes ( 17 ). 2. Apparatus according to claim 1, characterized in that the projections ( 40 ) owning press belt ( 32 ) in front of the Dop pelbandpresse ( 20 ) is preferred and at the same time as a conveyor belt for the multilayer arrangement layered structure ( 68 ) in the dop Pelband press ( 20 ) is used by the part of the press frame belonging to this press belt ( 32 ) at the inlet into the double belt press ( 20 ) is extended in a horizontal direction and the inlet-side deflection drum ( 36 ) for the press belt ( 32 ) is at the extreme end of this Extension located. 3. Apparatus according to claim 1 or 2, characterized in that the projections ( 40 ) corresponding to the fixing holes ( 17 ) are attached to the lower press belt ( 32 ). 4. Apparatus according to claim 1 or 2, characterized in that the projections ( 40 ) corresponding to the fixing holes ( 17 ) are attached to the upper press belt ( 31 ). 5. Apparatus according to claim 1 or 2, characterized in that both on the upper ( 31 ) and lower press belt ( 32 ) to the fixing holes ( 17 ) corresponding projections ( 40 ) are introduced. 6. Device according to one of claims 1 to 5, characterized in that the corresponding projections ( 40 ) as the press belt ( 31, 32 ) arranged pin teeth ( 56, 58, 60, 64 ) are formed. 7. The device according to claim 6, characterized in that the pin teeth ( 56, 58, 60, 64 ) are cylindrical. 8. The device according to claim 7, characterized in that the pin teeth ( 56, 60, 64 ) at the end of the press belt ( 32 ) abge tapered tapered. 9. Device according to one of claims 1 to 8, characterized in that the projections ( 40, 56, 58 ) corresponding to the fixing holes ( 17 ) are fixedly attached to the press belt ( 31, 32 ). 10. The device according to claim 9, characterized in that the projections ( 56 ) corresponding to the fixing holes ( 17 ) are welded to the press belt ( 32 ). 11. The device according to claim 9, characterized in that the projections ( 56 ) corresponding to the fixing holes ( 17 ) are soldered to the press belt ( 32 ). 12. The apparatus according to claim 9, characterized in that the projections ( 58 ) corresponding to the fixing holes ( 17 ) are glued to the press belt ( 32 ). 13. The device according to one of claims 1 to 8, characterized in that the fixing holes ( 17 ) correspon ding projections ( 40, 60, 64 ) on the press belt ( 31, 32 ) are interchangeably introduced. 14. The apparatus according to claim 13, characterized in that the projections ( 60 ) corresponding to the fixing holes ( 17 ) are screwed to the press belt ( 31, 32 ). 15. The apparatus according to claim 14, characterized in that the projection ( 60 ) has a press hole ( 32 ) facing thread hole ( 63 ) into which a countersunk screw ( 62 ) from the projection ( 60 ) facing away from the press belt ( 32 ) engages. 16. The apparatus according to claim 13, characterized in that the projection ( 64 ) has a press belt ( 32 ) facing groove ( 66 ) and with this groove ( 66 ) on a press belt ( 32 ) attached pin ( 65 ) . 17. The apparatus according to claim 16, characterized in that the pin ( 65 ) with the press belt ( 32 ) is welded or soldered ver. 18. The apparatus of claim 16 or 17, characterized in that both the pin ( 65 ) and the groove ( 66 ) have a circular cross section with approximately the same diameter.